In recent years a variety of electronic systems making use of switching regulators as part of the regulating functions of the system have come into use. These switching regulators are also used in many types of regulated power supply systems. There are, however, problems associated with switching regulators in that, since they are switched at very high frequencies, they have a tendency to introduce radio frequency interference (RFI) into their environment, into their D.C. outputs and sometimes back into the A.C. power supply source lines. The RFI problem is normally handled by substantial filtering and shielding which may involve substantial design and material costs if each regulator in the system is operating at a different frequency and without a synchronization pattern between the switching regulators.
Further, when a group of individual switching regulators, connected to a common voltage supply line, are used to supply different individual loads, a synchronized turn-on of power by each switching regulator would create a heavily severe instantaneous power demand. Thus, it would be desirable to have some means by which each individual regulator in the system would not turn-on at the same time as any of the other regulators in the system.
Accordingly, one feature of the invention is to provide improved means for controlling the switching frequency of two or more switching regulators in a manner so as to simplify the system filtering of radio frequency interference. Another feature of the invention is to provide improved means for controlling the phasing of the individual switching regulators so that the power demands of the various regulators occur at differently phased intervals rather than at the same time.